Well pumping assembly



Patented Aug. ll, 1942 wm fummo Assmann Edwin 0. Bennett, Ponca City, Okla., assignmto Continental Oil Company, Panca City, Okla., a

corporation of Delaware Application May 8, 1940, Serial No. 333,954

(Cl. i4-41;

ic'laims..

My invention relates to a well pumping assembly, land more particularly to an assembly for eliminatingrpeak stresses in the rods of Dumps for deep wells, such as oil wells.

Oil is recovered from most non-iiowing wells by means of reciprocating plunps operated by a line or string of rods called sucker rods. The loading on the rods varies 'during'differenty parts ci the stroke. At the beginning of the upstroke, the stress in the rods'frequently exceeds the normal pull required to raise both the rods and the load of oil by several thousand pounds. The

` peak stress thus set up does no useful work in lifting oil from the well. The subjecting of the rods to this stress shortens the liie of the rods and increases the .cost of pumping oil. Other stresses are occasioned by the harmonic motion I of the prime mover and by the resultant variations in acceleration during the pumping movements. l

The prime movers commonly employed for oil well pumping are constant speed machines such as internal combustion engines. In some pumping systems, induction motors are employed to operate the pumping mechanism. It` has been found, in pumping systems so operated, that rod breaking is an occurrence less frequently encountered. This is due to the' slip between the rotor of the induction motor and the revolving Ileld which occurs when acceleration changes placeincreased stress upon the rods.-

One object of my invention is to proyide a well pumping assembly in which stresses due to ace' celeration changes and peak loads are automat ically relieved electrically, enabling me to use a.

constant speed prime mover, of any suitable character.'

Another object of my invention is provide an oil well pumping assembly in which the pull or stresses on the rods may be limited to any desired predetermined value.

Referring now to drawing, the well casing is indicated diagrammatically by the refery ence numeral i. A walking beam 2 operates a string of sucker rods 3. The walking beam is oscillated around hearing Il hy a pitinan 5, which is connected to a crank E, driven through a reduction gear housed in casing l. An vinternal combustion engine, such as a Diesel engine, 8 is adapted. to furnish power through an electromagnetic coupling, indicated generally` bythe reference numeral 9, to driving pulley i0. The pulley ill is connected by multiple belts ii to pulley i2 mounted on a shaft i3, which drives the reduction gear train housed in housing l. The assembly is mounted upon a hed frame i4.

Referring new to Fig. 2, the prime mover 8 Y is provided with a Shaft l5 which drives the other and further objects of my invention wel appear from the following description.`

In the accompanying drawing which forms part or the instant speciilcation and is to be read in conjunction therewith, and in which like reference numerals are used to indicate like Darts in the various views; Fig. 1 is a side elevation of a pumping assembly showing one embodiment of my invention.

Fig. 2 is a diagrammatic end view with parts in section4 of a portion of the assembly shown in Fig. 1, on an enlarged scale.

Fig. 3 is a diagrammatic view showing a `detail of a control arrangement.

outer sectionY Si of an electro-magnetic coupling. 1

The outer section i5 is the muh-rel cage portion. The inner portion il of the electromagnetic coupling contains coils is. Torque set up between the section Il and the section l5 of the coupling is a function of the current ilowing through the windings of the coils i8. Exciting current is fed to the windings of the coils I8' through slip rings i! and 2B. .A rheostat 2l provides manual regulation of the exciting current. The current supplied :from any suitable source, such as a storage battery, transformer, generator, or the like, indicated diagrammatically as exciter and the reference numeral 22.

The amount of excitation current is adjusted to the torque delivered to the gear unit. This limitation will control the peak stresses can he induced the well pumping rods,

and will therefore prevent their breakage due to excessioading.

new to 3, E have shown one. means of automatically varying the excitation during s. single cycle theA slow speed shaft ci the gear unit, which cycle for the weli j pump rod- By referring to l, it will be seen t slo speed shalt is indicated by the reiern ence numero; 23, being nthe shaft to which the crank 3 is heyed. To the shaft 2-3 l secure a cam 2f! by stud'hclts 25, or in any other suitable manner. The cam is adapted to reciprocate e. iollower 23, the lower end which engages a pivoted arm 2l. The arm is urgedv upwardly ey means of a spring 2S, compressing a carbon pile l. lt is understood that any other suitable variable resistance may he employed.

The carbon pile 2B is in the circuit of the exthe rod is stationary.

.departingfromthe spirit citing coils `Il of the electromagnetic coupling. As the shaft 2l rotates the cam 24 will turn with lt and vary the compression which the spring 2l may exercise uponthe carbon pile Il.

The excitation current may be varied through any suitable range by the cam, or may be entirely interrupted during any part of the cycle by a'suitably designed cam. The current may be interrupted several times during a cycle i1 desired.l The angular position of the cam on the easily adjusted and the arthat high toi-ques and stresses rods may be entirely rangement is such normally occurring in pump eliminated.

A preferred and automatic means of controlling the torque input directly as a function oi the load is shown in Fig. 4, in which the reference numeral 3l indicates the polish rod, that is, the portion of the rod string which passes through the stuffing box Il. Clamps 32 and 3J are rigidly fastened to the polish rod 3l when The only stress in the rod between points l2 and static load of the rods. The clamps are provided with lateral extensions Il and 35 between which is positioned a carbon pile Il. The conductors 31 and 3l are secured to the carbon pile Vso that the exciting the carbon pile resistance;

When the pumping operation is started, an increase in the load on the rods. will cause an elongation.. increasing the resistance through the carbon pile and decreasing the exciting current.

Any change inthe length of the rod will vary the compression on the carbon pile resistor and alter the excitation current .invrseLv as a function of the load. When the load is great, the excitingcurrent will be less. When the load is small the exciting current will be great. Hence the maximum load taken by the rods is automatically adjusted thus limiting stresses and `giving longer life to the rod string with fewer fail- It will be seen that I have accomplished the objects of my invention. I have provided 4a deep well system in which peak stresses are automatically eliminated. I have further provided an electromagnetic torque control coupling in which the coupling is varied either in synchronism with the pump rods or automatically as a function of the load.

It will be understood that certain features and sub-combinations are of utility and may be employed without reference to other features and sub-combinations. is within the scope of my claims. It is further obvious that various changes may be made in details within the scope of my claims without of my invention. It is, to be understood that my invention is to the specific details *shown therefore.

not to 'be limited and described.

This is contemplated by and` of pumping rods 33 willbethatdue tothe Having' thus l. A pumping described my invention, i ciaim: assembly for wells having a line adapted to actuate a pump within the well, including in combination a prime mover, a. walking beam. means between the prime mover and walking beam for oscillating the same. said means including an electromagnetic coupling having an exciting coil, a source of potential for energizing said exciting coil, a resistance in series with said exciting coil. and means for varying said resistance directly as the stresses set up yin the pumping rods by the pumping op# eration.

2. A pumping assembly for wells having la line oi' pumping rods adapted w actuaie a pump Iwithin the well, including in combination a prime mover, a walking beam, means between the prime mover and walking beam for oscillating the same, said means including an electromagnetic coupling having an exciting coil. a source oi potential for energizing said exciting coil, a resistance in series with said exciting coil. a cam, means for moving said cam in timed relation with said pumping rods, said cam being shaped to increase said resistance at times of, increased stress in the pumping rods during the pumping operation,

v and to decrease said resistance .at times of recurrent must pass through duced stress in the pumping rods.

3,., A pumping assembly for wells having a line of pumping rods adapted to actuate a pump within the well, including`in combination a -prlme mover, a walking beam, means between the prime mover and walking beam for oscillating the same. said means including an' electromagnetic coupling having an exciting coil. a source of poten-v tial for energizing said exciting coil, a resistance in series with said exciting coil, means rigidly aiiixed to said rods at two spaced points therealong, and means carried by said last named means for .varying said resistance directly as the distance between said means hmxed to the rods.

4. In an oil well pumping assembly, a prime mover, a walking beam, a string of sucker rods reciprocad by said walking beam, means between said prime mover and said walking beam for oscillating the same, said means including an electromagnetic coupling having an exciting coil, a circuit for said exciting coil including a source of .potential and a variable resistance, a pair of clamps secured to said sucker rods at separated places therealong, said clamps supporting said variable resistance and having means for varying said resistance directly as elongation of said rods due to stresses imposed thereon, the construction being such that peak stresses are avoided due to the automatic variation of the electrognetic coupling inversely as the instantaneous EDWIN 0. BENNETT. 

